2 November 2021. Brains | Space

The more we know about the brain, the less we seem to understand. The accumulating amount of rubbish in space.

Welcome to Just Two Things, which I try to publish daily, five days a week. (For the next few weeks this might be four days a week while I do a course: we’ll see how it goes). Some links may also appear on my blog from time to time. Links to the main articles are in cross-heads as well as the story.

Apologies for missing yesterday’s edition. Circumstances beyond my control, etc.

#1: The more we know about the brain, the less we seem to understand

Nautilus has an article about the state of neuroscience which has some staggering numbers in. It seems that we can map part of the brains at least of small animals, but the amount of data it takes is off the scale. And even when we map it, we still don’t really understand what’s going on.

The author, Grigori Guitchonts, is a neuroscientist himself, working on rat brains at Harvard:

As a purplish-red sun set, I sat brooding over my dataset on rat brains... I have recorded the 13 trillion numbers in this dataset as part of my Ph.D. experiments, asking how the visual parts of the rat brain respond to movement. Printed on paper, the dataset would fill 116 billion pages, double-spaced. When I recently finished writing the story of my data, the magnum opus fit on fewer than two dozen printed pages.

This is an electron microscopy image of a slice of mouse cortex, which shows different neurons labeled by colour. Image: Lichtman Lab at Harvard, via Nautilus.

This sounds large enough, but it represents a tiny subset for the data that would record a whole brain. But that’s what neuroscientists are trying to do, using an impressive combination of nano-level research and machine learning. The goal here is to build a connectome, or a complete wiring diagram. Jeff Lichtman, a Harvard colleague of Guitchonts, is one of the leaders in this mapping endeavour. Some more numbers:

A complete wiring diagram for a mouse brain alone would take up two exabytes. That’s 2 billion gigabytes; by comparison, estimates of the data footprint of all books ever written come out to less than 100 terabytes, or 0.005 percent of a mouse brain. But Lichtman is not daunted. He is determined to map whole brains, exorbitant exabyte-scale storage be damned.

So the obvious question here is, if we could build a complete connectome, would we understand what was going on in the brain. Probably not, it turns out. Or at the very least it depends on what you mean by ‘understanding’:

“Most of us know what we mean when we say ‘I understand something’ (says Lichtman). It makes sense to us. We can hold the idea in our heads. We can explain it with language. But if I asked, ‘Do you understand New York City?’ you would probably respond, ‘What do you mean?’ There’s all this complexity. If you can’t understand New York City, it’s not because you can’t get access to the data. It’s just there’s so much going on at the same time. That’s what a human brain is. It’s millions of things happening simultaneously among different types of cells, neuromodulators, genetic components, things from the outside. There’s no point when you can suddenly say, ‘I now understand the brain,’ just as you wouldn’t say, ‘I now get New York City.’ ”

One of the problems—and this may reveal the limits of my understanding here—may be that the metaphor of the ‘wiring diagram’ isn’t completely helpful, since it implies a constant relationship between the different components, whereas the relationships between neurons are more complex, depending on the situation. And although we’ve had a complete wiring diagram of the 300-neuron worm C. elegans for seveal decades, we still don’t really understand how its brain connections relate to its behaviours.

There’s a bigger problem though, which is a philosophical one. As Guitchonts suggests to Lichtman, maybe our brains aren’t equipped to understand how our brains work:

“maybe there’s something fundamental about that idea: that no machine can have an output more sophisticated than itself,” Lichtman said... What a human brain does is trivial compared to its engineering. Which is the great irony here. We have this false belief there’s nothing in the universe that humans can’t understand because we have infinite intelligence. But if I asked you if your dog can understand something you’d say, ‘Well, my dog’s brain is small.’ Well, your brain is only a little bigger,” he continued, chuckling. “Why, suddenly, are you able to understand everything?”

This sends Guitchonts into a bit of spin in which the work of Borges and Magritte’s famous pipe painting get called as witnesses. The Magritte is apparently a neuroscience favourite.

But Lichtman, at least, says that even if we can’t build a full connectome, understanding the connections is still worthwhile:

There are many incurable diseases, such as schizophrenia, that don’t have a biomarker related to the brain. They’re probably related to brain wiring but we don’t know what’s wrong. We don’t have a medical model of them. We have no pathology.

So it might be that even having parts of the wiring diagram might help us to understand better what’s going on when the brain starts to malfunction. But, of course, it might not. We might need a completely different model.

#2: The accumulating amount of rubbish in space

There’s a striking chart from McKinsey on the rapidly accumulating amount of debris accumulating in space. This is going to get worse, not so much because of billionaire-financed space trips but because of the way space-based comms is likely to be structured.

Something like 11,000 satellites have been launched since 1957–though one-tenth of those went up in 2020. This number is about to increase rapidly:

Now we’re at the point where about 70,000 satellites could enter orbit if proposed plans come to fruition—an explosion of interest based on potential new markets, innovative architectures, and more sophisticated technologies. Even if all the proposed constellations fail to deploy, many more satellites will be in space. Unless actively deorbited, they will remain there for months to hundreds of years, depending on the altitude.

There are multiple problems here. In theory, space is pretty large area, and against that metric, 27,000 pieces of tracked space debris doesn’t seem a big deal.

But there’s also an awful lot of untracked debris, and relatively small pieces can do quite a lot of harm to routine space activities:

Given the speed at which orbital objects move, even a collision between small debris and another object on a crossing trajectory can be catastrophic. The International Space Station (ISS), which is designed to survive impacts by debris up to one centimeter in diameter, was damaged in May 2021 when an object about five millimeters in size punched a hole in the thermal covering of its robotic arm.

The problem of increasing debris has been discussed since the 1960s—there’s a hypothesis called the Kessler Syndrome, named for its inventor, that posits that above a certain level of space debris, we’ll see cascading and unpredictable effects.

The issue has started gaining attention, if not actual action, since a collision between a live and a defunct satellite in 2009 blew into 20,000 pieces of debris.

The US had a 2011 report; the United Nations has produced recommendations on managing space sustainable; and the G7 inter-governmental meeting in 2021 in Cornwall produced a report and recommended international co-operation to manage the problem. (Which sounds like a perfect G7 type report...)

McKinsey is McKinsey, so their article finishes with a crisp set of bullet-pointed recommendations, paraphrased here:

- Better management and tracking of active satellites, and agreement on ‘end of life’ disposal;

- A plan to remove end-of-life and defunct satellites;

- Changes to the design of satellites so they are more likely to survive a collision with small debris;

- Approaches to start removing small debris, where sensor technology is starting to catch up.

It’s hard to read this, however, without thinking that it’s just another example of humans dumping stuff into the environment and not taking responsibility for it. It will need some kind of international co-ordination to make it happen.

Ah, the governance of space! Well, that happens to be another area where things haven’t quite kept up with technologies. There are quite a few links on this (Atlantic Council and Carnegie Endowment for International Peace , for example) but that’s for another time.

j2t#198

If you are enjoying Just Two Things, please do send it on to a friend or colleague.